[OSM-talk] OSM on Mobile Phones (and beyond!)
osm at fop.ns.ca
Tue Jul 3 18:23:46 BST 2007
On Mon, 2 Jul 2007, tim wrote:
> In preparation for my talk at SOTM on "OSM on Your Phone", I'd like to
> know if you've come across, used, or have thoughts on Openstreetmap
> with mobile phones.
Treo 650 with both Lowrance iFinder (NMEA through serial cable) and a
BGT-11 (NMEA over Bluetooth). CetusGPS and CotoGPS are reasonably good but
with their flaws (Cetus is a pain to delete previous points, for example).
For mapping, I've been experimenting with Pathaway GPS
(http://www.pathaway.com/) and managed to figure out a rather tedious way
to get maps into it that aren't so large they won't fit on my Treo:
1. Use the osm2ozi_tah.pl app (see
http://wiki.openstreetmap.org/index.php/Oziexplorer) to generate the map
and calibration files, like so:
./osm2ozi_tah.pl -tilename="11,661,739" -tilesource="http://dev.openstreetmap.org/~ojw/Tiles/tile.php"
2. Next, reduce the image to monochrome. Load the image into Gimp, and
click Image, Mode, Indexed and check "Use black and white (1-bit) palette"
and set "Color dithering" to "Floyd-Steinberg (reduced color bleeding)".
Save the image as the same filename (otherwise the calibration file will
3. Load the resulting image into the Pathaway Map Manager (runs fine under
File, Import New Map, select the file you just saved, set Color Depth to
1-bit (BW), check Compressed, click OK.
It will now grind through the image while it converts it from 1 bit to 1
bit again. Unfortunately the algorithm used in Pathaway is somewhat
lacking, so if full colour images are used the dithering goes wonky - or
it creates a huge map file. Once it's done, the image needs to be
Click Calibration, Calibration type Lat/Long (rectangular), Coordinate
type top left and bottom right (ignore any popup messages about losing
current calibration), the lat/lon fields should magically autopopulate.
Click File, Save Pathaway Map, save the map (as a prc for Palm - not sure
I tried Trekbuddy but it didn't seem to want to work with the IBM JVM for
Palm. I vaguely recall hearing of a freeware app that did calibration of
raster images, but I can't recall enough detail to turn up anything useful
in Google - if this rings a bell with anyone else I'd be interested as I'm
sure the general principle of osm2ozi_tah can be extended to other
> For example, in addition to collecting gpx traces and displaying
> rendered maps, I could have osm data editing on-the-fly as I walk down
> the road. Also, I'm thinking it would be great to be able to tell if,
> when I'm on a street/area, if that street/area has already been mapped
> via text.....
This method lets me see what's been mapped up to the point the map was
created, I can see how updating on the fly would be nice. The only problem
is graphics - I stuck Google Maps on my Treo and thought it was quite
nifty to wander around mapping on the Treo, until I saw the megs and megs
of data that were downloaded - on a 10 meg data plan, that was most of the
month gone in 20 minutes!
More information about the talk